Large-scale Field Tests Research Articles

A new approach for improving lateral performance of pile foundations in seasonally frozen regions

Ground freezing in cold areas can cause brittle damage to deep foundations during seismic loading. This paper presents a novel solution to this problem by replacing local soil around the pile with a temperature-insensitive composite material, namely polyurethane glue-bonded rubber particles-sand mixture (PolyBRUS). Three 1/12 scale reinforced concrete pile foundations embedded in unfrozen, frozen, and frozen with local replacement conditions were prepared, and quasi-static cyclic loading tests were conducted to reveal the adverse effects of seasonal freezing on pile foundations and verify the performance of the proposed solution. The model preparation, including model pile configuration, model construction, sensor configuration, and frozen soil formation, were described in detail. The pile foundation lateral performance data, including failure mode observations, lateral load-displacement hysteresis relations, and moment distributions, were presented. The evolution of secant stiffness and energy dissipation of the pile-soil system with lateral displacement were analyzed and discussed. It was found that the peak lateral load of the model pile in 20 cm-thick seasonal frost is 53% larger than the unfrozen conditions. In contrast, the ultimate displacement in seasonally frozen conditions is 25% less than that in unfrozen conditions. And seasonal freezing can render a pile from ductile to brittle failure. More importantly, the results show that the local replacement with the proposed material can ensure similar lateral behavior for the soil-pile system under both unfrozen and frozen conditions. It is concluded that the proposed local replacement approach offers excellent potential for mitigating the adverse effects of seasonal freezing on the lateral performance of deep foundations in cold regions. In future studies, local replacement zone optimization and large-scale field tests are recommended to further confirm this method's effectiveness and provide design parameters for pilot testing.

From Warfighting Needs to Robot Actuation: A Complete Rapid Integration Swarming Solution

Swarm robotics systems have the potential to transform warfighting in urban environments but until now have not seen large-scale field testing. We present the Rapid Integration Swarming Ecosystem (rise), a platform for future multi-agent research and deployment. rise enables rapid integration of third-party swarm tactics and behaviors, which was demonstrated using both physical and simulated swarms. Our physical testbed is composed of more than 250 networked heterogeneous agents and has been extensively tested in mock warfare scenarios at five urban combat training ranges. rise implements live, virtual, constructive simulation capabilities to allow the use of both virtual and physical agents simultaneously, while our “fluid fidelity” simulation enables adaptive scaling between low and high fidelity simulation levels based on dynamic runtime requirements. Both virtual and physical agents are controlled with a unified gesture-based interface that enables a greater than 150:1 agent-to-operator ratio. Through this interface, we enable efficient swarm-based mission execution. rise translates mission needs to robot actuation with rapid tactic integration, a reliable testbed, and efficient operation.

Development of GeoGebra-Based Learning Media for Flat Field Analytical Geometry Courses for Students of the Mathematics Education Department

All aspects of life, including the education system, have undergone many changes due to the Covid-19 pandemic. We need media that can facilitate and attract students to carry out learning activities. This study aims to develop GeoGebra-based mathematics learning media. The method used in this research is Research and Development (R&D) with the ADDIE model (Analysis, Design, Develop, Implement, and Evaluate). The research was carried out at UIN Sayyid Ali Rahmatullah Mathematics Study Program in semester 3. The research subjects for the small-scale field test were class A, which had 32 students; for the large-scale field test, there were 132 students in Mathematics Education 3rd Semester. The results of research on the development of GeoGebra-based learning media in the Flat Analytical Geometry course for students majoring in Mathematics Education at UIN Sayyid Ali Rahmatullah Tulungagung were declared valid, practical and effective. The future hope for developing similar media is to expand the scope of the material discussed because the media developed is limited to flat analytic geometry operations.

Long-Term Antimicrobial Performance of Textiles Coated with ZnO and TiO2 Nanoparticles in a Tropical Climate.

This paper reports the results of the large-scale field testing of composite materials with antibacterial properties in a tropical climate. The composite materials, based on a cotton fabric with a coating of metal oxide nanoparticles (TiO2 and/or ZnO), were produced using high-power ultrasonic treatment. The antibacterial properties of the materials were studied in laboratory tests on solid and liquid nutrient media using bacteria of different taxonomic groups (Escherichia coli, Chromobacterium violaceum, Pseudomonas chlororaphis). On solid media, the coatings were able to achieve a >50% decrease in the number of bacteria. The field tests were carried out in a tropical climate, at the Climate test station "Hoa Lac" (Hanoi city, Vietnam). The composite materials demonstrated long-term antibacterial activity in the tropical climate: the number of microorganisms remained within the range of 1-3% in comparison with the control sample for the duration of the experiment (3 months). Ten of the microorganisms that most frequently occurred on the surface of the coated textiles were identified. The bacteria were harmless, while the fungi were pathogenic and contributed to fabric deterioration. Tensile strength deterioration was also studied, with the fabrics coated with metal oxides demonstrating a better preservation of their mechanical characteristics over time, (there was a 42% tensile strength decrease for the reference non-coated sample and a 21% decrease for the sample with a ZnO + CTAB coating).

Design of an Er-doped surface plasmon resonance-photonic crystal fiber to improve magnetic field sensitivity.

In order to meet the demand for large-scale magnetic field testing, this paper proposes a D-shaped magneto-refractive photonic crystal fiber (MRPCF) based on surface plasmon resonance (SPR) by using the erbium-doped materials. The four different structures of Models A, B, C, and D are designed by changing the diameter, the position, and the number of layers of the air holes, and the corresponding magnetic field sensing characteristics are analyzed. The results show that in the magnetic field range of 5-405 mT, the magnetic field sensitivities of Models A, B, C, and D are 28 pm/mT, 48 pm/mT, 36 pm/mT, and 21 pm/mT, respectively. Meanwhile, the figure of merit (FOM) of the four MRPCF-SPR sensors is investigated, which have FOMs of 4.8 × 10-4 mT-1, 6.4 × 10-4 mT-1, 1.9 × 10-4 mT-1, 0.9 × 10-4 mT-1. Model B has higher sensitivity and larger FOM. In addition, the effect of the structural parameters of Model B on the sensing performance is also studied. By optimizing each parameter, the magnetic field sensitivity of the optimized Model B is increased to 53 pm/mT, and its magneto-refractive sensitivity and FOM are 2.27 × 10-6 RIU/mT and 6.2 × 10-4 mT-1, respectively. It shows that the magneto-refractive effect of MRPCF can be effectively enhanced by optimizing the structural design of fiber. The proposed MRPCF is an all-solid-state fiber, which solves the instability problem of the magnetic fluid-filled fiber and reduces the complexity of the fabrication process. The all-solid-state MRPCF can be used in the development of quasi-distributed optical fiber magnetic field sensors and has broad applications in the fields of geological exploration, earthquake and tsunami monitoring, and military navigation.

Establishment and application of a CRISPR-Cas12a-based RPA-LFS and fluorescence for the detection of Trichomonas vaginalis

BackgroundInfection with Trichomonas vaginalis can lead to cervicitis, urethritis, pelvic inflammatory disease, prostatitis and perinatal complications and increased risk of HIV transmission. Here, we used an RPA-based CRISPR-Cas12a assay system in combination with a lateral flow strip (LFS) (referred to as RPA-CRISPR-Cas12a) to establish a highly sensitive and field-ready assay and evaluated its ability to detect clinical samples.MethodsWe developed a one-pot CRISPR-Cas12a combined with RPA-based field detection technology for T. vaginalis, chose actin as the target gene to design crRNA and designed RPA primers based on the crRNA binding site. The specificity of the method was demonstrated by detecting genomes from nine pathogens. To improve the usability and visualize the RPA-CRISPR-Cas12a assay results, both fluorescence detection and LFS readouts were devised.ResultsThe RPA-CRISPR-Cas12a assay platform was completed within 60 min and had a maximum detection limit of 1 copy/µl and no cross-reactivity with Candida albicans, Mycoplasma hominis, Neisseria gonorrhoeae, Escherichia coli, Cryptosporidium parvum, G. duodenalis or Toxoplasma gondii after specificity validation. Thirty human vaginal secretions were tested by RPA-CRISPR-Cas12a assays, and the results were read by a fluorescent reporter and LFS biosensors and then compared to the results from nested PCR detection of these samples. Both RPA-CRISPR-Cas12a assays showed 26.7% (8/30) T. vaginalis-positive samples and a consistency of 100% (8/8). The RPA-CRISPR-Cas12a assays had a higher sensitivity than nested PCR (only seven T. vaginalis-positive samples were detected).ConclusionsThe T. vaginalis RPA-CRISPR-Cas12a assay platform in this study can be used for large-scale field testing and on-site tests without the need for trained technicians or costly ancillary equipment.Graphical abstract

Seismic characterization of a landslide dam failure hazard chain: Insights into flow dynamics and implications for warning

Landslide dam failure hazard chains (i.e., landslide dam breaches → outburst debris flow → river blocking) are common in alpine valley regions worldwide, and they pose a great threat to human safety and infrastructure. However, the formation and dynamic processes of cascading hazards are still poorly understood, which limits our ability to recognize warning signals for this multi-hazard chain. We conducted 12 large-scale field tests on the multi-hazard chain induced by landslide dam failure, measuring the flow dynamics and the resulting seismic signals. The results showed that river blockage caused by a dam-breaching debris-flow underwent stages of injection and initial deposition, river damming and equilibration, during which the evolution of seismic signals can help interpret the physical processes and mechanisms involved. The radiated energy level resulting from the dam breaching and the debris flow increased with the diameter, speed and volume of the fluid-particles mixture; while the frequency of the seismic data increased with the speed of the fluid-mixture particles but decreased with the diameter of the particles. Greater tributary inflow discharge or dam height generally resulted in larger and more destructive outburst debris flows, characterized by greater seismic energy and a wider frequency domain, resulting in a greater degree of obstruction within the receiving channel. We also show that the seismic technique employed is an efficient means of detecting and characterizing landslide dam failure hazard chains, providing downstream warnings of a river blockage by estimating the critical blockage conditions, such as the tributary flow velocity, sediment concentration, and kinetic energy. This study provides a scientific perspective for understanding the dynamic signatures of the entire hazard chain evolutionary process and it highlights opportunities to use seismic data for multi-hazard chain research and warning.

Soil arching effect in reinforced piled embankment for motor-racing circuit: Field tests and numerical analysis

When constructing superstructures on soft soils, severe issues including excessive settlements, bearing failures, and large lateral displacements arise and cause challenges for geotechnical engineers. Reinforced piled embankments are being used increasingly for various types of engineering construction such as highway widening and roadway construction, thereby making it crucial to comprehend and evaluate systematically the effect of soil arching, which has a significant influence on the performance of such embankments. This study focuses on two large-scale field tests of the piled embankments for an international motor-racing circuit in China, and the effect of the load transfer platform formed by geosynthetic reinforcement and gravel layer is investigated. Field monitoring data of soil pressures and settlements of pile caps and soils are reported and analyzed, and the test results show that soil arching acts significantly to transfer the load to the pile caps with an increase in loading from the embankment. Geogrids within the gravel layer can not only improve soil arching (reflected by higher stress concentration ratio) but also diminish differential settlements between pile caps and the ground surface. A numerical test considering different influencing factors is also conducted, thereby enabling both studying the effects of varying the field parameters and comparing with the insitu measurements. A proposed numerical model of the reinforced piled embankment is also shown to work well when compared with the results of the field tests. This study enhances the comprehension of soil–pile–geogrid interactions and guides similar projects in the future.

Active and Passive Earth Pressure Calculation Method for Double-Row Piles considering the Nonlinear Pile Deformation

The double-row pile supporting structure has been widely used in foundation pit excavations. When analyzing the effect of earth pressure on the pile structure, previous research only considered the double-row piles as the rigid body and the pile-soil interaction has not been examined. In this study, a theoretical model was developed based on Duncan-Chang’s hyperbolic theory to calculate earth pressures in the active and passive zones of the double-row pile supporting structure. The model considered the nonlinear effect of the pile deformation on the active and passive earth pressures. The macroscopic pile-soil interaction was converted into a microscopic stress-strain relationship at a certain point in the soil body, reflecting the nonlinear effect of pile deformation on earth pressure. Numerical simulation and large-scale field tests have been conducted to verify the proposed model. The results show that the average values of the parameters obtained by numerical simulation are a ¯ = 0.38 , b ¯ = − 0.253 for the active zone and a ¯ = 0.00612 , b ¯ = − 0.729 for the passive zone. Based on the values of a ¯ and b ¯ , the predicted active and passive earth pressures stemming from the developed model agreed well with those obtained from field tests. The developed model in this study can be used to predict the distribution of active and passive earth pressures for double-row pile supporting structures.

Field experimental investigation on broadband vibration mitigation using metamaterial-based barrier-foundation system

Both periodic barriers and periodic foundations can be used as passive isolation measures to reduce the unfavorable vibrations affecting the protected superstructure. Under a certain direction of excitation, the frequency band gaps provided by the periodic barriers and periodic foundations are usually distinguishable due to the different orientations of these subsurface structures. In this study, a series of field tests are conducted to assess the combined usage of the periodic barrier and periodic foundation in a manner to achieve better wave isolation effect. Both periodic barrier and periodic foundation used in this study are made of one-dimensional (1-D) layered periodic material. Using the state-of-art hydraulic mobile shaker (T-Rex), the excitation with various types of input signals can be applied in all the three orthogonal directions at the desired location. The arrangement of motion sensors allows for recording the response of the ground surface and the protected superstructure in all the three directions. The screening effectiveness, quantified as Frequency Response Function (FRF), of the periodic barrier and periodic foundation are discussed separately, followed by an overall evaluation of the wave isolation performance of the system composed of both periodic barrier and periodic foundation. The results show that the filtering capability of the periodic barrier and the periodic foundation is complementary to each other, and the combined usage of the periodic barrier and the periodic foundation is beneficial to mitigating the vibration of the protected superstructure. ∙ A novel large-scale field tests reported on wave isolation of periodic barriers and periodic foundations. ∙ State-of-art shaker (T-Rex) is adopted to apply triaxial excitation and triaxial soil velocity are collected. ∙ The composite isolation effect of periodic barrier-periodic foundation system is first reported. ∙ Various excitations lead to similar isolation results for the periodic barrier and periodic foundation. ∙ The addition of periodic foundation will not adversely affect the performance of periodic barrier.

Lignin–Chitosan Nanocarriers for the Delivery of Bioactive Natural Products against Wood-Decay Phytopathogens

The use of nanocarriers (NCs), i.e., nanomaterials capable of encapsulating drugs and releasing them selectively, is an emerging field in agriculture. In this study, the synthesis, characterization, and in vitro and in vivo testing of biodegradable NCs loaded with natural bioactive products was investigated for the control of certain phytopathogens responsible for wood degradation. In particular, NCs based on methacrylated lignin and chitosan oligomers, loaded with extracts from Rubia tinctorum, Silybum marianum, Equisetum arvense, and Urtica dioica, were first assayed in vitro against Neofusicoccum parvum, an aggressive fungus that causes cankers and diebacks in numerous woody hosts around the world. The in vitro antimicrobial activity of the most effective treatment was further explored against another fungal pathogen and two bacteria related to trunk diseases: Diplodia seriata, Xylophilus ampelinus, and Pseudomonas syringae pv. syringae, respectively. Subsequently, it was evaluated in field conditions, in which it was applied by endotherapy for the control of grapevine trunk diseases. In the in vitro mycelial growth inhibition tests, the NCs loaded with R. tinctorum resulted in EC90 concentrations of 65.8 and 91.0 μg·mL−1 against N. parvum and D. seriata, respectively. Concerning their antibacterial activity, a minimum inhibitory concentration of 37.5 μg·mL−1 was obtained for this treatment against both phytopathogens. Upon application via endotherapy on 20-year-old grapevines with clear esca and Botryosphaeria decay symptoms, no phytotoxicity effects were observed (according to SPAD and chlorophyll fluorescence measurements) and the sugar content of the grape juice was not affected either. Nonetheless, the treatment led to a noticeable decrease in foliar symptoms as well as a higher yield in the treated arms as compared to the control arms (3177 vs. 1932 g/arm), suggestive of high efficacy. Given the advantages in terms of controlled release and antimicrobial product savings, these biodegradable NCs loaded with natural extracts may deserve further research in large-scale field tests.

Brief Report: Creation of a Transition Readiness Scale for Adolescents with ASD.

The transition to postsecondary education is characterized by many changes for adolescents with autism spectrum disorder (ASD). A data-based understanding of a student's readiness for postsecondary education could help students, and their parents, better prepare for this life transition. The Transition Readiness Scale (TRS) was created to address this need. The TRS is a self/other-report questionnaire used to assess postsecondary readiness across behavioral, cognitive, and emotional domains among adolescents 15-18years of age. The present study details measure development and provides preliminary psychometric properties in a sample of transition-aged youth with ASD. Results indicate strong internal consistency, adequate item-level analyses, and discriminant and concurrent validity. Future validation of the TRS in large-scale field testing is merited to inform clinical interpretation.

Large Scale Direct Shear Box Tests on Gravels

The determination of shear strength characteristics of gravelly soils is difficult through the use of conventional small scale, triaxial or simple shear testing devices in the laboratory due to membrane compliance and boundary effects; or due to inconsistent penetration resistances measured as part of standard or cone penetration testing in the field. These limitations require the use of available empirical or semi-empirical relationships or the execution of large scale laboratory or field tests. In the literature there exists inconsistent, and large range of recommendations for shear strength parameters. Within the confines of this study, direct shear box test results performed on poorly- (GP) and well-graded (GW) gravel samples with initial void ratio ranging from 0.42 to 0.53 are presented, which are tested under effective normal stresses ranging from 77 to 205 kPa. The estimated peak secant-angles of shearing resistances vary in the range of 49 to 54 degrees. On the basis of volumetric change vs. shear strain responses, the peak angle of dilation and elastic Poisson’s ratio are estimated to vary in the range of 10-16 degrees and 0.28-0.39, respectively. These estimated values are compared with available literature.

Numerical modelling of rammed aggregate piers (RAP) in liquefiable soil

Liquefaction poses a significant risk to the built environment, and as a result, ground improvement (GI) techniques are commonly used to mitigate this risk. Liquefaction mitigation strategies continually evolve, and several relatively new techniques, such as Rammed Aggregate Piers® (RAP), have shown promise. While the densification mechanism associated with many of the GI techniques is generally well known, other mechanisms such as reinforcement, lateral stress increase, and improved drainage that are thought to enhance liquefaction mitigation are still not completely understood. Moreover, field performance data for these GI schemes during actual earthquakes is limited. To fill this gap and evaluate the performance of RAP, this study presents the first numerical model on a specific GI technique that uses detailed site characterization, large-scale field test data, and post-earthquake field performance observations to calibrate and qualitatively validate the model. The in-situ characterization and full-scale field test data collected from the Ground Improvement Programme (GIP) performed following the 2010–2011 Canterbury Earthquake Sequence (CES) in New Zealand are used in this study. A set of fully-coupled hydro-mechanical finite difference (FD) models are performed in natural and reinforced conditions. For the unimproved soil profile, the results predict shear strains and zones of high excess pore water pressures reasonably well. For the profile reinforced with RAP, the analyses indicate that the stiffness properties of the RAP have the greatest influence on the reduction of generated shear strains in the soil profile. Finally, the calibrated models are subjected to a set of ground motions with different intensities to assess the efficacy of the RAP under different loading conditions.

Shifting Perspectives of Translational Research in Bio-Bactericides: Reviewing the Bacillus amyloliquefaciens Paradigm.

Bacterial biological control agents (BCAs) have been increasingly used against plant diseases. The traditional approach to manufacturing such commercial products was based on the selection of bacterial species able to produce secondary metabolites that inhibit mainly fungal growth in optimal media. Such species are required to be massively produced and sustain long-term self-storage. The endpoint of this pipeline is large-scale field tests in which BCAs are handled as any other pesticide. Despite recent knowledge of the importance of BCA-host-microbiome interactions to trigger plant defenses and allow colonization, holistic approaches to maximize their potential are still in their infancy. There is a gap in scientific knowledge between experiments in controlled conditions for optimal BCA and pathogen growth and the nutrient-limited field conditions in which they face niche microbiota competition. Moreover, BCAs are considered to be safe by competent authorities and the public, with no side effects to the environment; the OneHealth impact of their application is understudied. This review summarizes the state of the art in BCA research and how current knowledge and new biotechnological tools have impacted BCA development and application. Future challenges, such as their combinational use and ability to ameliorate plant stress are also discussed. Addressing such challenges would establish their long-term use as centerfold agricultural pesticides and plant growth promoters.

Development and Validation of a Survey Instrument Targeting Teachers’ Perceptions of the Scope of Engineering

Around the world, pre-college teachers are increasingly being called upon to address engineering, often as part of science instruction. Teachers are typically tasked with engaging students in authentic engineering design activities to promote students’ development of design practices while deepening their knowledge of relevant science concepts. Planning and implementing engineering experiences that authentically reflect the field require that teachers hold accurate perceptions of what engineering is, how it works, and how it is related to yet distinct from science. As teacher education and research efforts in this area grow, there is a need for high-quality instruments that elicit key aspects of how teachers think about engineering. However, few instruments are currently available, and each has significant limitations. This study presents a new instrument, the Scope of Engineering Survey, that addresses a critical dimension of teachers’ perceptions of engineering. The ‘‘scope of engineering’’ refers to the kinds of projects and activities that do and do not fall under the umbrella of engineering work. Individuals who hold accurate views on the scope of engineering understand the breadth of engineering work, but can also differentiate engineering work from that of technicians or scientists. This is essential for teachers, because holding accurate views on the scope of engineering places them in a far better position to design and implement authentic engineering activities in their classrooms. This study describes how the Scope of Engineering Survey was developed, provides evidence of the validity and reliability of the instrument, and gives recommendations for its future uses. Results from a large-scale field test are reported and baseline statistics are provided for key survey measures.

Experimental study of using Aerogel insulation for residential buildings

ABSTRACT Nowadays energy saving has become one of the most compelling sectors in the world. Thermal insulation of buildings presents an effective solution for energy conservation. Aerogel insulation is the most advanced insulation material for building application. Having low thermal conductivity around 15 mW/(m.K), high resistance to perforation, and flexibility to be cut and adapt at building site make Aerogel one of the most promising thermal insulations. In this paper, the feasibility of using Aerogel blankets as a super insulator has been experimentally verified using small scale laboratory test, large scale field test and high-fidelity computer simulations using Energy-Plus. A reduction in energy use by 23% and 38% was observed when using single (10 mm) and double (20 mm) layers of aerogel, respectively for a period of one year. Furthermore, payback analysis confirmed the effectiveness of using Aerogel. Aerogel insulation will help engineers to build energy efficient buildings.

Robust identification of low-Cd rice varieties by boosting the genotypic effect of grain Cd accumulation in combination with marker-assisted selection

Rice (Oryza sativa L.), a staple for half of the world’s population, usually accumulates high levels of cadmium (Cd) in the grain when planted in the Cd-contaminated paddy fields. Genetic improvements using natural variation of grain-Cd accumulation is the most cost-effective way to mitigate the risk of excess Cd accumulation. However, as a complex trait, grain-Cd accumulation is susceptible to environmental variation, which challenges to characterize the genetic nature and subsequently the stable performance of grain-Cd accumulation. To boost the genetic effect on grain-Cd performance, we established an approach of normalization using the comparative grain-Cd value (CCd) following a contrasting field design. Identification of the genetic locus responsible for CCd variation help us develop a low-grain-Cd variety de novo, named ‘Lushansimiao’, which had lower grain-Cd levels in a large-scale field test and can produce Cd-safe rice following prolonged irrigations in the field with intermediate levels of Cd pollution. Combined CCd evaluating and low-Cd allelic genotyping, another six varieties were also identified as low-grain-Cd rice. Our study paves the way to efficiently quantify the genetic nature of grain-Cd accumulation in rice, and the stable low-Cd rice varieties will help to mitigate the risk of excess Cd accumulation in rice.

Terrestrial LiDAR system accuracy investigation for slow-moving landslide deformation

Landslides are a special kind of geological hazard found throughout the entire world. The methods to predict the timing of landsliding and to study its kinematics or consequences are timely topics in research. Terrestrial laser scanning technology has been used for predicting and researching geological hazards for two decades. This research focuses on using terrestrial light detection and ranging (LiDAR) to measure the slow-moving displacement of both the surface and the subsurface soil of landslides and investigating LiDAR system accuracy. Physical modeling was done to simulate the performance of special targets mounted on rods driven into an active landslide, measured using terrestrial LiDAR to improve the scanning accuracy. The primary conclusions from this research are as follows: (1) several tests were done to prove that the terrestrial three-dimensional LiDAR scanner used in this research can precisely obtain the three-dimensional position, displacement, and rotational angle of scanning targets, which can present shallow surface movement of slow-moving landslides. (2) Two kinds of special scanning targets were used for the laser scanner to measure the displacement of surface and subsurface soil in sandbox tests. These consist of spherical Styrofoam targets mounted on rigid metal rods driven into the soil to help the LiDAR scanner improve the accuracy of scanning results and obtain the shallow surface soil movement in the test model. (3) A large-scale field test was designed to prove the feasibility of extending the function of the LiDAR system to obtain the shallow subsurface displacement of landslides and improve the accuracy of the scanning results.

Primary energy efficiency potentials of district heat driven refrigeration systems

District heat driven absorption chillers (AChs) contribute to a higher utilisation of the district heating network in summer and thus to a reduction of the relative heat losses. Due to higher investment but lower operating costs, AChs usually cover the base load, but compression chillers (CChs) are installed for peak load as well. For ACh and CCh, heat rejection is often realised via cooling towers (CTs). In addition, many systems provide the option of free cooling in winter by using the cooling towers to cover the cooling demand directly. Thus, absorption cooling (AC), compression cooling (CC) and free cooling (FC) represent three operating modes for cold generation in one overall refrigeration system. The concept of allocating base load and peak load is usually realised by activating CC when AC exceeds the capacity limit. FC is activated when the ambient temperature falls below a certain switchover value.In this study, extensive monitoring data from a large-scale field test (“Field test absorption chillers for CCHP systems”) are used to show that refrigeration systems controlled in such or similar ways have considerable potential to increase primary energy efficiency, even if the individual chillers are operated efficiently. Therefore, models are applied to the individual primary components (ACh, CCh, CT and auxiliary pumps). By using these models, thermal and/or electrical part-load efficiencies of AC, CC and FC and their specific dependencies on the ambient temperature and chilled water set temperature are calculated. Taking into account district heating and electricity primary energy factors allows to determine the operating mode with the lowest primary energy demand for each load condition measured in the field test within one year. The savings potential of 14% resulting from this example shows how promising the application of a model-based system control is compared to conventional strategies.